“None.”
“It is a logical explanation?”
“There is no evidence against it.”
“And you feel someone tried to murder you because you had this information?”
“It is a possibility.”
They were silent for nearly a minute, then Mason said, “I want to think that over. In the meantime, I’m going to get my sleeping bag spread out.”
Mason walked over to the car, pulled out the sleeping bags, fitted the power pump to the motor, inflated the air mattresses, and looked up to find Salty Bowers at his side.
“Have you,” Mason asked, “staked out any particular sleeping quarters?”
“We’ve got a tent,” Salty said. “The girls can use it for a dressing-room. They won’t want to sleep in it. It’s better to sleep out under the stars.”
“Then let’s put Miss Street’s sleeping bag over by the tent,” Mason said. “Where are you sleeping?”
Salty lowered his voice. “I’m not too easy in my mind about what’s been going on. I’ve pulled my blankets down the trail a piece where I can sort of keep watch in case anybody should come pussyfooting along. — You pick up that end of the sleeping bag, I’ll pick up this end and we’ll carry it over. And when we get done, the tea will be just about ready to drink.”
When the sleeping bags had been placed in position and the duffel bags brought out of Mason’s car, the little group gathered once more around the fire. Salty put an armful of sagebrush on the fire, which promptly crackled into brilliance, a circle of illumination chasing back the encroaching shadows.
Salty poured tea, said, “The air’s different out here somehow.”
“It most certainly is,” Mason said. “Dry and clear.”
“A few months ago I developed a sinus condition,” Dr. Kenward said. “It’s clearing up out here with great rapidity. I am most encouraged.”
“How’s the wound?” Mason asked.
“Nothing serious at all. I have to watch for certain complications and nip them in the bud if they arise. I naturally have to be quiet. Believe it or not, this is a great boon to me. It’s an enforced vacation, but a very welcome one.”
“What’s Nell Sims doing?” Mason asked. “Staying in the house?”
“Staying in the house nothing,” Salty said. “She headed back to Mojave, says she’s going to open up her old restaurant. I guess,” he added wistfully, “the desert has a way of reclaiming its own.”
“It’s marvelous out here,” Della said.
“Lots of people hate the desert,” Salty explained. “That’s because they’re really afraid of it. They’re afraid of being left alone with themselves. There’s lots of people you could put down in the middle of the desert, go away and leave ’em for a week, and come back and find them completely crazy. I’ve seen it happen. Man sprained his ankle once, couldn’t travel. The party he was with had to go right on, but they left him with lots of water and food, plenty of matches, lots of wood. All he had to do was to just keep quiet for three or four days until he got so he could travel. He showed up in civilization just about half crazy. His ankle was all inflamed, said he’d rather have lost the whole leg than to have stayed on in that desert for another ten minutes.”
“I think it’s beautiful,” Velma Starler said.
“Sure it’s beautiful,” Salty agreed. “People get scared of it because out here they’re alone with their Maker. Some people can’t stand that. — How about some more tea?”
The sagebrush finished its preliminary crackling, got down to a steady burning.
“How,” Mason asked, “do you go about prospecting? Do you just wander around and look the desert over?”
“Gosh, no. You have to know a little something about how the ground was formed. You’ve got to figure out your formations, and then you’ve got to know what to look for. Lots of prospectors have picked up rock that would have made them rich, and thrown it away. — Here, let me show you something.”
Salty put down his teacup, got up and walked over to the pickup. He rummaged around for a few moments, then produced a boxlike affair.
“What’s that?” Mason asked.
“Black light. Ever seen it work?”
“I’ve seen it used in connection with the detection of forgeries.”
“If you ain’t seen it in the desert, you just ain’t seen anything. We’ve got to have it where it’s dark. Come on, walk around behind this rock outcropping and I’ll show you.”
“I’ll plead my crippled condition and stay here,” Dr. Kenward said. “I don’t want too much getting up and down.”
They moved around behind the big rock outcropping. Here the light of the fire was shut out, and the stars, blazing with steady brilliance, seemed interested spectators regarding with a steady scrutiny the vague figures that moved over the desert.
Salty noticed them looking at the stars. “They say stars twinkle when air is mixed up with dust and stuff, and different air currents make ’em twinkle. I don’t know anything about it. Maybe some of you folks do. All I know is that they don’t twinkle out here.”
Salty clicked a switch. A low humming sound came from the interior of the machine.
“Sort of induction coil,” Salty explained. “Steps the current up from six volts to a hundred and fifteen. There’s a two-watt bulb in here. It’s on now.”
The darkness assumed a peculiar color. It was hardly an illumination, was as though the darkness had turned a deep, almost black, violet.
“Now,” Salty said, “I’ll turn this beam of invisible light over toward this rock outcropping and you see what happens.”
He swung toward the outcropping, turning the boxlike arrangement with his body as he pivoted.
Almost immediately it seemed that a thousand different colored lights had been turned on in the rocky outcropping. Some of the lights were blue, some a yellowish green, some a bright green. The lights varied in size from small pin points to great blobs of illumination the size of a baseball.
Della Street caught her breath. Velma Starler exclaimed out loud. Mason was silent, fascinated by the spectacle.
“What is it?” Della Street asked.
“I don’t know too much about it. They call it fluorescent light,” Salty said. “We use it in prospecting. You can tell different minerals by the different colors. I’ll admit that I sort of fixed up the face of that rock outcropping a little bit, putting in some float I picked up in other parts of the desert that didn’t rightly belong there.
“You were asking me about prospecting. We do a lot of it at night now. Lug around one of these outfits and spot minerals with it. Rocks that you’d pass over by day without a second glance will show you they’ve got valuable mineral in ’em when you turn this black light on ’em. — Well, let’s go back to the fire. I don’t want the Doc to think we ran away and left him. I just wanted to show you.”
Salty switched off the mechanism which made the black light.
“Well,” Dr. Kenward asked as they returned to the campfire, “how about it? Did it work?”
“Wonderfully,” Mason said.
“It was the most awe-inspiring, the most beautiful sight I’ve ever seen,” Velma Starler said enthusiastically. “Do you know how it works?”
“Generally. A bulb filled with argon and having a very low current consumption, usually about a two-watt-current rating, emits ultraviolet light. Our eyes aren’t adjusted so we can see this light, but when it impinges upon various minerals, the wave length is changed back to that of visible light. The result is that these minerals have the appearance of actually emitting rays of light of various colors as independent sources of illumination.”
“You’ve used those machines?” Mason asked him.
“I— Ouch! A twinge of pain in that leg. It’s all right, Velma... nothing to be done.”